JPH01502618A - Light beam deflection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] In-plane device of luminous flux Technical field The present invention uses a rotatable turning prism of constant deflection about an axis to A focusing device combined with this turning prism, especially an F-theta (F-theta) objective This invention relates to a device that polarizes a beam of light using a lens.

technical level A large number of such devices are used in scanning devices. In known scanning devices, there is no light source. The light beam emerging from the beam is deflected by a rotating deflection member and scanned using a focusing device. It is focused as a point of light on the surface of the object. The light flux is transformed by the rotating turning member, e.g. For example, it is deflected to one plane. The scanning of the surface is performed in a line.

In this type of optical scanning device, the scanning line is a straight line, and the scanning lines that follow one above the other are interchangeable. It is necessary that the lines be provided in parallel to each other, and that the distance between the lines be constant. practically Deviations from the ideal movement pattern of the recording point always occur. Therefore, for example, fraud Turning parts stored in a properly constructed warehouse are flutter. and moved into an oscillatory motion (head). Such effects depend on the accuracy of the scanning device. impede movement.

A pentaprism that rotates around an axis that passes through one of its mutually orthogonal sides. It is known to compensate for the disturbing effects of a tripod head with the help of. This penta The prism achieves a constant beam deflection that is independent of the tilt of the prism axis of rotation. to be accomplished. This application of a pentaprism within a scanning device is described, for example, in US Pat. No. 475.787.

This kind of pentaprism is designed to the smallest diameter so that the entrance of the subsequent focusing device If the cutting width is made as small as possible, the periodic characteristic of the rotated pentaprism is Not satisfied. This is a particularly large flaw. This is because the pentaprism is This is because it rotates at a relatively high rotational speed. Therefore, expensive balancing of the drive motor and/or The speed is limited by the relatively low rotational speed of the deflecting member due to the high centrifugal forces.

The main object of the present invention is to easily produce the type mentioned at the beginning with excellent equilibrium properties. The purpose is to provide a turning prism.

This problem is solved by the fact that the turning prism according to the present invention is a four-sided prism according to Wollaston. or its axis of rotation is approximately relative to one surface of both prism surfaces forming a right angle to each other. This is solved by being orthogonally oriented.

Inside a device of the type mentioned at the outset, a four-sided prism known per se by Wollaston is used. If so, the distance between the axis of rotation and the center of gravity of this prism, the weight of the prism, and the The distance between the axis of rotation and the part of the prism furthest from the axis of rotation determines the In this regard, it has been found that a surprisingly favorable configuration of the deflection member can be achieved. minimum Compared to the pentaprism designed to the dimensions, the four-sided prism by Wollaston is , even less weight. The entrance focus section of the subsequent focusing device is equal to the maximum entrance focal length required for the system. However, Wollaston's four-cornered The rhythm is that the mechanical center of gravity of the square prism becomes extremely close to the center of gravity of parallel incident light. It is particularly important to be able to position the Because this priz The prism is rotated around the center of gravity of the incident parallel rays, so it is This is because there is no longer any disequilibrium in all cases. Therefore, the balance is particularly high at high speeds. The properties are significantly improved.

A four-sided prism by Wollaston consists of two evaporated and two non-evaporated surfaces. It has a face. Adjacent non-evaporated surfaces are at a 90' angle to each other. sandwich.

Basically speaking, a beam of light that is oriented parallel to the axis of rotation is It enters this square prism through a first undeposited surface that is approximately vertical; It is reflected by another deposition surface on the deposition surface adjacent to the surface that is not deposited, and ends up being a second deposition surface. It is allowed to exit the square prism through the surface that is not deposited.

However, the optimally small entrance focus section of the focusing device is particularly important in the present invention as indicated in claim 2. This can be achieved with the configuration of the invention.

Correct and complete deflection of the luminous flux can be maintained even in the case of tilting of the prism rotation axis. , the entrance surface of the square prism is selected to be larger than the beam cross-section. Preferences of the present invention In a new embodiment, both prism surfaces oriented orthogonally to each other are It has the width claimed in claim 3 in the direction orthogonal to the line.

Further preferred embodiments of the invention are indicated in claims 4 and 5.

Brief description of the drawing The present invention will be exemplarily described below based on the accompanying drawings.

In the figure, Figure 1 is a cross-sectional view of a conventional pentaprism, and Figure 2 is a square drawn by Wollaston. FIG. 3 is a cross-sectional view of a prism.

Description of examples In both figures, a deflecting prism is shown, which is to deflect the incident light beam by 90%. both In the heating diagram, neither the focusing device nor the mounting and indicating portions of each prism are shown. Puri The focusing device combined with the prism is installed in the front or rear of the prism in its optical path. can be done.

In FIG. 1, both surfaces 1.2 which are not deposited, both surfaces 3.4 which are deposited and another surface 5. It shows. A beam of light, e.g. a laser beam with diameter d, is applied to the surface not to be deposited. 1 and enters this pentaprism. After reflection from both deposited surfaces 3 and 4, The laser beam exits this pentaprism via the surface 2 which is not deposited. three This pentaprism, which indicates the beam of this luminous flux with reference symbol 6.7.8, around an axis whose position coincides with the position of the beam 7 oriented perpendicular to the plane 1 rotates. The position of the center of gravity, whose distance to surface 2 is denoted by Sp, is characterized by S. The spacing between plane 0 2 and planes 4 and 5 is denoted by t.

In FIG. 2, a four-sided prism made by Wollaston is shown. This prism , two undeposited surfaces 9.10 and two deposited surfaces 11.1 forming a right angle. I have 2. Their surfaces 10.11 and their surfaces 9.12 are located at corner 6 7.5° in between.

The luminous flux, of which only beams 13, 14, 15 are represented, is directed vertically through surface 9. If it is incident on the square prism, it will be reflected by the vapor deposition surface 11 and then the surface Totally reflected at surface 10.9 0 After reflection at surface 12, this beam exits from surface 10 . This emitted light beam is bent by 90° compared to the incident light beam. This optical axis 14 is also the rotation axis of the square prism. This axis of rotation is approximately perpendicular to the prism surface 9. oriented crosswise, i.e. its axis of rotation is at most angularly 4°- Insert -, which depends on the refraction value of the glass.

FIG. 2 shows an ideal case of a rotation axis that is not tilted. The incident light beams overlap each other. and parallel to the surface 10.

The distance between the surface 10 and the cross image of surfaces 9 and 12 is indicated by a.

In this embodiment, the light beam has a distance 1XVo of, for example, 0.15d with respect to the surface 10. It is equipped with The distance This is necessary by maintaining complete conversion.

The beam deflection performed by this square prism is sensitive to the prism rotation axis. It's not a feeling. Even in the case of tilt, the angle between the emitted light flux and the incident light flux is opposite to each other. and can only be moved in parallel. With the focusing device described below, in this example the scanning device Efutator (rhata) - an optical device that focuses mutually parallel beams of light.

Compared to the pentaprism, the center of gravity of the four-sided prism by Wollaston (surface 10 The distance 1 sW) from the center of gravity of the pentaprism rotation axis is the square prism. The square prism is very close to the axis of rotation, so this square prism is no longer completely unbalanced. stomach. Therefore, especially at high rotational speeds, its equilibrium properties are significantly better than that of a pentaprism. Improved.

The distances Mj and a are identical, in other words the same population for the focusing device in both cases. Generate cutting width.

Takaramo II 1st trial report international search report Dmiεεkuku: 22

Claims (1)

[Claims] 1. Redirection into one plane using a rotatable rotating prism with constant deflection around an axis A focusing device combined with a prism, especially a Theta objective lens. In a device that deflects a beam of light with The turning prism is a four-sided prism made by Wollaston, and The axis of rotation is approximately perpendicular to one surface of both prism surfaces forming a right angle to each other. A device characterized in that it is oriented. 2. The four-sided prism has two undeposited surfaces and two evaporated surfaces sandwiching right angles from each other. The above-mentioned square prism with a fixed surface has a constant refractive index, and in this case, the prism has a fixed refractive index. to this square prism via a substantially parallel oriented and first undeposited surface (9). A light beam enters and is reflected by the first vapor deposition surface (11) facing the incident surface (9). (13, 14, 15) are first totally reflected on the second undeposited surface (10), and then After being totally reflected on the first non-evaporated surface (9), the light beam reaches the second deposition surface (12). After reflection at , it exits this square prism via a second undeposited surface (10). 2. Device according to claim 1, characterized by a combination of the above features. 3. Both prism surfaces (9, 10) oriented orthogonally to each other lie at their intersection line. at least one width in the direction orthogonal to a=(1+2X)■d■√2 with here d = diameter of the luminous flux and Claim 1 characterized in that 0.05≦X≦0.3, especially 0.1≦X≦0.2. or the device described in 2. 4. Claims 1 to 3, wherein the light flux axis is a rotation axis of the four-sided prism. 3. The device according to any one of 3. 5. This four-sided prism is designed for a turning angle of only 90° of the luminous flux. The device according to any one of claims 1 to 4, characterized in that: